Substrate processing apparatus and substrate processing method

ABSTRACT

A substrate processing apparatus includes a rotary table arranged in a vacuum chamber, a first reaction gas supply unit that supplies a first reaction gas to a surface of the rotary table, a second reaction gas supply unit that is arranged apart from the first reaction gas supply unit that supplies a second reaction gas, which reacts with the first reaction gas, to the rotary table surface, an activated gas supply unit that is arranged apart from the first and second reaction gas supply units and includes a discharge unit that supplies an activated etching gas to the rotary table surface, and a plurality of purge gas supply units that are provided near the discharge unit for supplying a purge gas to the rotary table surface. A flow rate of the purge gas supplied from each of the purge gas supply units can be independently controlled.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a substrate processingapparatus and a substrate processing method.

2. Description of the Related Art

With the miniaturization of circuit patterns of semiconductor devices,there is a growing demand for techniques for reducing the thickness andimproving the uniformity of various films constituting semiconductordevices. In view of such a demand, the so-called molecular layerdeposition (MLD) method or the atom layer deposition (ALD) method isknown as a film forming method that involves supplying a first reactiongas to a substrate to cause adsorption of the first reaction gas to thesurface of the substrate, then supplying a second reaction gas to thesubstrate to cause a reaction between the first reaction gas that isadsorbed on the surface of the substrate and the second reaction gas,and depositing a film that is made of the reaction product on thesubstrate (e.g., see Japanese Laid-Open Patent Publication No.2010-56470).

According to the above film forming method, the reaction gas may beadsorbed to the surface of the substrate in a (quasi) self-saturatingmanner such that high film thickness controllability, desirableuniformity, and desirable embedding characteristics may be achieved.

However, in view of the miniaturization of circuit patterns, forexample, as the aspect ratio of a space in a line/space patternincreases in a trench element separation structure, it becomesincreasingly difficult to embed a film in a trench or a space even whenthe MLD method or the ALD method is used.

For example, when embedding a space having a width of about 30 nm in asilicon oxide film, it may be difficult to introduce a reaction gas tothe bottom of such a narrow space, and as a result, the film thicknessat the upper end portions of line side walls defining the space mayincrease. Thus, in some cases, a void may be created in the siliconoxide film having a space embedded by a film. When such a silicon oxidefilm is etched in a subsequent etching process, for example, an openingcommunicating with the void may be formed at the upper surface of thesilicon oxide film. In such case, an etching gas (or etching solution)may enter the void through the opening to cause contamination, or ametal may enter the void during a metallization process performedthereafter to create defects, for example.

The occurrence of such a problem is not limited to the case of using theMLD method or the ALD method, but may also occur in the case of using achemical vapor deposition (CVD) method. For example, when embedding afilm made of conductive material in a contact hole that is formed in asemiconductor substrate to create a conductive contact hole (a so-calledplug), a void may be formed in the plug. In this respect, a method offorming a conductive contact hole while preventing the formation of sucha void in the conductive contact hole is known. For example, whenembedding a conductive material in a contact hole to form a conductivecontact hole, an etch back process may be repeatedly performed to removeany overhanging portion of the conductive material that is formed aroundthe upper end of the contact hole (e.g., see Japanese Laid-Open PatentPublication No. 2003-142484).

However, according to the method described in Japanese Laid-Open PatentPublication No. 2003-142484, the process of forming the conductivematerial film and the etch back process have to be performed indifferent apparatuses. Thus, time is required in transporting thesubstrate back and forth between the apparatuses and stabilizing processconditions in each apparatus such that throughput cannot be increased.

Also, a film forming apparatus and a film forming method are known thatmay solve the above problems of the method described in JapaneseLaid-Open Patent Publication No. 2003-142484. The film forming apparatusand the film forming method enable embedding at a high throughput whilereducing the occurrence of voids in a concave pattern formed on thesurface of a substrate. The film forming apparatus includes a rotarytable on which a substrate is mounted, first and second gas supply unitsthat are capable of supplying first and second reaction gases for filmformation to a substrate mounting surface of the rotary table, and anactivated gas supply unit that activates and supplies a modification gasfor modifying a reaction product generated by a reaction between thefirst and second reaction gases and an etching gas used for etching. Thefilm formation method involves using such a film forming apparatus tosuccessively repeat the processes of film formation, modification, andetching within the same processing chamber through rotation of therotary table (e.g., see Japanese Laid-Open Patent Publication No.2012-209394).

However, in the film forming method described in Japanese Laid-OpenPatent Publication No. 2012-209394, the etching amount distribution inthe substrate surface cannot be adequately controlled, and it isdifficult to achieve etching uniformity in the substrate surface.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a substrate processingapparatus that is capable of controlling an etching amount distributionin within a substrate surface.

According to one embodiment of the present invention, a substrateprocessing apparatus is provided that includes a vacuum chamber; arotary table that is rotatably arranged in the vacuum chamber to hold asubstrate; a first reaction gas supply unit that supplied a firstreaction gas to a surface of the rotary table; a second reaction gassupply unit that is arranged apart from the first reaction gas supplyunit in a circumferential direction of the rotary table and supplies asecond reaction gas, which reacts with the first reaction gas, to thesurface of the rotary table; an activated gas supply unit that isarranged apart from the first reaction gas supply unit and the secondreaction gas supply unit in the circumferential direction of the rotarytable; and a plurality of purge gas supply units. The activated gassupply unit includes a discharge unit having a discharge hole throughwhich an activated etching gas is supplied to the surface of the rotarytable. The plurality of purge gas supply units are arranged close to thedischarge hole with respect to the circumferential direction of therotary table and supply a purge gas to the surface of the rotary table.A flow rate of the purge gas that is supplied from each of the pluralityof purge gas supply units can be independently controlled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a substrate processingapparatus according to an embodiment of the present invention;

FIG. 2 is a schematic plan view of the substrate processing apparatus;

FIG. 3 is a partial cross-sectional view illustrating separation regionsin the substrate processing apparatus;

FIG. 4 is another partial cross-sectional view of the substrateprocessing apparatus;

FIG. 5 is a partial cross-sectional view illustrating a third processregion of the substrate processing apparatus;

FIG. 6 another schematic plan view of the substrate processingapparatus;

FIG. 7 a partial cross-sectional view illustrating purge gas supplyunits of the substrate processing apparatus;

FIGS. 8A-8D are diagrams showing simulation results of a fluorine volumefraction within a vacuum chamber during an etching process;

FIGS. 9A-9C are diagrams showing other simulation results of thefluorine volume fraction within the vacuum chamber during an etchingprocess; and

FIGS. 10A-10D are diagrams showing other simulation results of thefluorine volume fraction within the vacuum chamber during an etchingprocess.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the present invention will be describedwith reference to the accompanying drawings. Note that in the followingdescriptions and the accompanying drawings, elements havingsubstantially the same functional features are given the same referencenumerals and overlapping descriptions thereof may be omitted.

(Substrate Processing Apparatus Configuration)

In the following, the configuration of a substrate processing apparatusaccording to an embodiment of the present invention is described. FIG. 1is a schematic cross-sectional view of the substrate processingapparatus according to the present embodiment. FIG. 2 is a schematicplan view of the substrate processing apparatus according to the presentembodiment. FIG. 3 is a partial cross-sectional view illustratingseparation regions of the substrate processing apparatus according tothe present embodiment. FIG. 4 is another partial cross-sectional viewof the substrate processing apparatus according to the presentembodiment.

As illustrated in FIGS. 1 and 2, the substrate processing apparatusaccording to the present embodiment includes a vacuum chamber 1 having asubstantially circular plane shape, and a rotary table 2 that isarranged within the vacuum chamber 1 such that the center of the vacuumchamber 1 corresponds to the rotational center of the rotary table 2.

The vacuum chamber 1 includes a chamber body 12 having a cylindricalshape with a bottom, and a ceiling plate 11 that is detachably arrangedon an upper surface of the chamber body 12 and is sealed airtight to theupper surface via a sealing member 13 such as an O-ring.

The rotary table 2 has a center portion that is fixed to a cylindricalcore portion 21. The core portion 21 is fixed to an upper end of arotary shaft 22 extending in the vertical direction. The rotary shaft 22penetrates through a bottom portion 14 of the vacuum chamber 1 and has alower end that is attached to a drive unit 23 for rotating the rotaryshaft 22 around a vertical axis. The rotary shaft 22 and the drive unit23 are accommodated in a cylindrical case 20 having an opening formed atits upper face. The case 20 has a flange portion formed at its upperface that is attached airtight to a bottom surface of the bottom portion14 of the vacuum chamber 1, and in this way, an internal atmospherewithin the case 20 may be maintained airtight from an externalatmosphere of the case 20.

As illustrated in FIG. 2, a plurality (e.g., 5 in the illustratedexample) of circular concave portions 24 that are capable ofaccommodating a plurality of semiconductor wafers corresponding tosubstrates (hereinafter referred to as “wafer W”) are arranged along arotational direction (circumferential direction) on the surface of therotary table 2. Note that in FIG. 2, for convenience, the wafer W isillustrated in only one of the concave portions 24. The concave portion24 has an inner diameter that is slightly larger (e.g., larger by 4 mm)than the diameter of the wafer W (e.g., 300 mm), and a depth that isapproximately equal to the thickness of the wafer W. Thus, when thewafer W is placed in the concave portion 24, the surface of the wafer Wand the surface of the rotary table 2 (i.e., surface of the region wherethe wafer W is not placed) may be substantially flush. Also, a number(e.g., 3) of through holes (not shown) are formed at a bottom face ofthe concave portion 24 such that lift pins (not shown) for supportingthe rear face of the wafer W and lifting the wafer W may be arranged topenetrate through the through holes.

Also, as illustrated in FIG. 2, reaction gas nozzles 31 and 32,separation gas nozzles 41 and 42, and an activated gas supply unit 90are arranged above the rotary table 2. In the illustrated example, theactivated gas supply unit 90, the separation gas nozzle 41, the reactiongas nozzle 31, the separation gas nozzle 42, and the reaction gas nozzle32 are spaced apart along the circumferential direction of the vacuumchamber 1 in this order as viewed clockwise (rotational direction of therotary table 2) from a transfer port 15 (described below). Note that thereaction gas nozzle 31 is an example of a first reaction gas supplyunit, and the reaction gas nozzle 32 is an example of a second reactiongas supply unit.

The reaction gas nozzles 31 and 32 respectively include a gasintroduction ports 31 a and 32 a corresponding to base portions that arefixed to an outer peripheral wall of the chamber body 12. The reactiongas nozzles 31 and 32 are introduced into the vacuum chamber 1 from theouter peripheral wall of the vacuum chamber 1. Also, the reaction gasnozzles 31 and 32 are arranged to extend parallel with respect to therotating table 2 along the radial directions of the chamber body 12.

The separation gas nozzles 41 and 42 respectively include gasintroduction ports 41 a and 42 a corresponding to base portions that arefixed to the outer peripheral wall of the chamber body 12. Theseparation gas nozzles 41 and 42 are introduced into the vacuum chamber1 from the outer peripheral wall of the vacuum chamber 1. The separationgas nozzles 41 and 42 are arranged to extend parallel with respect tothe rotary table 2 along the radial directions of the chamber body 12.

Note that the activated gas supply unit 90 is described below.

The reaction gas nozzle 31 may be made of quartz, for example, and isconnected to a supply source of a Si (silicon)-containing gas that isused as a first reaction gas via a pipe and a flow regulator (notshown), for example. The reaction gas nozzle 32 may be made of quartz,for example, and is connected to a supply source of an oxidizing gasthat is used as a second reaction gas via a pipe and a flow regulator(not shown), for example. The separation gas nozzles 41 and 42 are eachconnected to supply sources of separation gases via a pipe and a flowrate regulating valve (not shown), for example.

An organic amino silane gas may be used as the Si-containing gas, and O₃(ozone) gas or O₂ (oxygen) gas may be used as the oxidizing gas, forexample. Also, N₂ (nitrogen) gas and Ar (argon) gas may be used as theseparation gases, for example.

The reaction gas nozzles 31 and 32 have a plurality of gas dischargeholes 33 that open toward the rotary table 2 (see FIG. 3). The gasdischarge holes 33 may be arranged at intervals of 10 mm, for example,along the length direction of the reaction gas nozzles 31 and 32, forexample. A lower region of the reaction gas nozzle 31 corresponds to afirst process region P1 for causing adsorption of the Si-containing gasto the wafer W. A lower region of the reaction gas nozzle 32 correspondsto a second process region P2 for oxidizing the Si-containing gas thathas been adsorbed to the wafer W at the first process region P1.

Referring to FIG. 2, convex portions 4 protruding toward the rotarytable 2 from bottom face regions of the ceiling plate 11 near theseparation gas nozzles 41 and 42 are provided in the vacuum chamber 1.The convex portions 4 and the separation gas nozzles 41 and 42 formseparation regions D. The convex portion 4 is fan-shaped in planar viewand has a top portion that is cut into a circular arc shape. In thepresent embodiment, the inner arc of the convex portion 4 is connectedto a protruding portion 5 (described below) and the outer arc of theconvex portion 4 is arranged along an inner peripheral surface of thechamber body 12 of the vacuum chamber 1.

FIG. 3 is a partial cross-sectional view of the vacuum chamber 1 along aconcentric circle of the rotary table 2 from the reaction gas nozzle 31to the reaction gas nozzle 32. As illustrated in FIG. 3, the vacuumchamber 1 includes a first ceiling surface 44 corresponding to thebottom face of the convex portion 4 that is low and flat, and a secondceiling surface 45 that is higher than the first ceiling surface 44 andis arranged at both sides of the first ceiling surface 44 in thecircumferential direction.

The first ceiling surface 44 is fan-shaped in planar view and has a topportion that is cut into a circular arc shape. Also, as illustrated inFIG. 3, a groove portion 43 extending in a radial direction is formed atthe circumferential direction center of the convex portion 4, and theseparation gas nozzle 42 is accommodated within this groove portion 43.Note that another groove portion 43 is similarly formed in the otherconvex portion 4, and the separation gas nozzle 41 is accommodatedwithin this groove portion 43. Also, the reaction gas nozzles 31 and 32are arranged in spaces below the higher second ceiling surface 45. Thereaction gas nozzles 31 and 32 are spaced apart from the second ceilingsurface 45 to be arranged close to the wafer W. Note that forconvenience of explanation, the space below the higher second ceilingsurface 45 where the reaction gas nozzle 31 is arranged is representedas “space 481”, the space below the higher second ceiling surface 45where the reaction gas nozzle 32 is arranged is represented as “space482” (see FIG. 3).

The first ceiling surface 44 forms a separation space H corresponding toa narrow space between the first ceiling surface 44 and the surface ofthe rotary table 2. The separation space H can separate theSi-containing gas supplied from the first region P1 and the oxidizinggas supplied from the second region P2 from each other. Specifically,when N₂ gas is discharged from the separation gas nozzle 42, the N₂ gasdischarged from the separation gas nozzle 42 flows toward the space 481and the space 482 through the separation space H. At this time, becausethe N₂ gas flows through the narrow separation space H that has asmaller volume compared to the spaces 481 and 482, the pressure in theseparation space H can be made higher than the pressure in the spaces481 and 482. That is, a pressure barrier may be created between thespaces 481 and 482. Also, the N₂ gas flowing from the separation space Hinto the spaces 481 and 482 act as counter-flows against the flow of theSi-containing gas from the first area P1 and the flow of the oxidizinggas from the second region P2. Thus, the Si-containing gas and theoxidizing gas may be substantially prevented from flowing into theseparation space H. In this way, the Si-containing gas and the oxidizinggas are prevented from mixing and reacting with each other in the vacuumchamber 1.

Referring to FIG. 2, the protruding portion 5 is arranged around anouter periphery of the core portion 21 that fixes the rotary table 2,and the protruding portion 5 is arranged on the bottom surface of theceiling plate 11. In the present embodiment, the protruding portion 5 isconnected to a rotational center side portion of the convex portion 4,and a bottom surface of the protruding portion 5 is arranged to be flushwith the first ceiling surface 44.

Note that for convenience of explanation, FIG. 2 illustrates across-section of the chamber body 12 cut along a position that is higherthan the second ceiling surface 45 and lower than the separation gasnozzles 41 and 42.

FIG. 1 referred to above is a cross-sectional view of the substrateprocessing apparatus along line I-I′ of FIG. 2 illustrating a regionwhere the second ceiling surface 45 is arranged. On the other hand, FIG.4 is a partial cross-sectional view of the substrate processingapparatus illustrating a region where the first ceiling surface 44 isarranged.

As illustrated in FIG. 4, a bent portion 46 that is bent into an L-shapeto face an outer edge face of the rotary table 2 is formed at aperipheral portion (portion toward the outer edge of the vacuum chamber1) of the fan-shaped convex portion 4. The bent portion 46, like theconvex portion 4, prevents the two reaction gases from entering theseparation space H from both sides of the separation area D and preventsthe two reaction gases from mixing with each other. The fan-shapedconvex portion 4 is arranged at the ceiling plate 11, and the ceilingplate 11 is arranged to be detachable from the chamber body 12. Thus, aslight gap is formed between an outer peripheral face of the bentportion 46 and the chamber body 12. Note that dimensions of a gapbetween an inner peripheral face of the bent portion 46 and an outeredge face of the rotary table 2, and the gap between the outerperipheral face of the bent portion 46 and the chamber body 12 may besubstantially the same as the height dimension of the first ceilingsurface 44 with respect to the surface of the rotary table 2, forexample.

In the separation region D, an inner peripheral wall of the chamber body12 is arranged into a substantially vertical plane that is in closeproximity with the outer peripheral face of the bent portion 46 asillustrated in FIG. 4. Note, however, that in regions other than theseparation region D, the inner peripheral wall of the chamber body 12may have a portion recessed outward from a region facing the outer edgeface of the rotary table 12 to the bottom portion 14 as illustrated inFIG. 1, for example. In the following, for convenience of explanation,such a recessed portion having a rectangular cross section is referredto as “exhaust region E”. More specifically, the exhaust region E thatcommunicates with the first process region P1 is referred to as “firstexhaust region E1”, and the exhaust region E that communicates with thesecond process region P2 is referred to as “second exhaust region E2” asillustrated in FIG. 2. Further, a first exhaust port 61 and a secondexhaust port 62 are respectively formed at the bottom of the firstexhaust region E1 and the second exhaust region E2. As illustrated inFIG. 1, the first exhaust port 61 and the second exhaust port 62 areeach connected to a vacuum exhaust unit such as a vacuum pump 64 via anexhaust pipe 63. Also, a pressure regulating unit 65 is arranged at theexhaust pipe 63.

As illustrated in FIGS. 1 and 4, a heater unit 7 as a heating unit maybe arranged in a space between the rotary table 2 and the bottom portion14 of the vacuum chamber 1, and a wafer W arranged on the rotary table 2may be heated to a predetermined temperature according to a processrecipe via the rotary table 2. Also, a ring-shaped cover member 71 forpreventing gas from entering a lower region of the rotary table 2 isarranged at a lower side of a peripheral edge portion of the rotarytable 2. The cover member 71 acts as a partition member for separatingthe atmosphere of a region extending from the space above the rotarytable 2 to the exhaust regions E1 and E2 and the atmosphere of a spacewhere the heater unit 7 is arranged.

The cover member 71 includes an inner member 71 a that faces an outeredge portion of the rotary table 2 and a portion extending furtheroutward from this outer edge portion from the lower side, and an outermember 71 b that is arranged between the inner member 71 a and an innerwall face of the vacuum chamber 1. In the separation region D, the outermember 71 b is arranged near the bent portion 46, at the lower side ofthe bent portion 46, which is formed at the outer edge portion of theconvex portion 4. The inner member 71 a surrounds the entire peripheryof the heater unit 7 at the lower side of the outer edge portion of therotary table 2 (and the portion extending slightly outward from theouter edge portion).

A protruding portion 12 a is formed at a part of the bottom portion 14toward the rotational center side of the space where the heater unit 7is disposed. The protrusion 12 a protrudes upward toward the coreportion 21 at a center portion of the bottom surface of the rotary table2. A narrow space is formed between the protrusion 12 a and the coreportion 21. Also, a narrow space is provided between an outer peripheralface of the rotary shaft 22 that penetrates through the bottom portion14 and an inner peripheral face of a through hole for the rotary shaft22. Such narrow spaces are arranged to be in communication with the case20. Further, a purge gas supply pipe 72 for supplying N₂ gas as a purgegas is arranged at the case 20.

Also, a plurality of purge gas supply pipes 73 for purging the spaceaccommodating the heater unit 7 are arranged at the bottom portion 14 ofthe vacuum chamber 1 at intervals of a predetermined angle along thecircumferential direction below the heater unit 7 (only one of the purgegas supply pipes 73 is illustrated in FIG. 4). Also, a lid member 7 a isarranged between the heater unit 7 and the rotating table 2 in order toprevent gas from entering the region where the heater unit 7 is located.The lid member 7 a extends in the circumferential direction to cover aregion between an inner wall of the outer member 71 b (upper face of theinner member 71 a) and an upper edge portion of the protrusion 12 a. Thelid member 7 a may be made of quartz, for example.

Also, a separation gas supply pipe 51 is connected to a center portionof the ceiling plate 11 of the vacuum chamber 1. The separation gassupply pipe 51 supplies N₂ gas as a separation gas to a space 52 betweenthe ceiling plate 11 and the core portion 21. The separation gassupplied to the space 52 is discharged toward the periphery of therotary table 2 along a wafer mounting area side surface of the rotarytable 2 via a narrow space 50 between the protruding portion 5 and therotary table 2. The pressure within the space 50 can be maintained at ahigher pressure than the pressure within the space 481 and the space 482by the separation gas. That is, by providing the space 50, theSi-containing gas supplied to the first process region P1 and theoxidizing gas supplied to the second process region P2 may be preventedfrom passing through a center region C (see FIG. 1) to mix with eachother. In other words, the space 50 (or the center region C) may have afunction similar to that of the separation space H (or separation regionD).

Further, as illustrated in FIG. 2, the transfer port 15 for transferringthe wafer W corresponding to a substrate between an external transferarm 10 and the rotary table 2 is arranged at a side wall of the vacuumchamber 1. The transfer port 15 may be opened/closed by a gate valve(not shown). Note that the wafer W may be transferred back and forthbetween the concave portion 24 corresponding to the wafer mountingregion of the rotary table 2 and the transfer arm 10 when the concaveportion 24 is positioned to face the transfer port 15. Accordingly, liftpins that penetrate through the concave portion 24 to lift the wafer Wfrom its rear face and a lift mechanism for the lift pins (not shown)are arranged at a portion below the rotary table 2 corresponding to atransfer position for transferring the wafer W.

In the following, the activated gas supply unit 90 is described withreference to FIGS. 2 and 5-7. FIG. 5 is a partial cross-sectional viewillustrating a third process region P3 of the substrate processingapparatus according to the present embodiment. FIG. 6 is a schematicplan view of the substrate processing apparatus according to the presentembodiment. FIG. 7 is a partial cross-sectional view illustrating purgegas supply units 96 of the substrate processing apparatus according tothe present embodiment. Note that FIG. 6 illustrates a state in whichthe plasma generation unit 91 and the etching gas supply unit 92 areremoved from the substrate processing apparatus illustrated in FIG. 2.Also, FIG. 7 illustrates a cross-section of FIG. 6 along line J-J′.

The activated gas supply unit 90 supplies an activated etching gas to afilm formed on the wafer W to etch the film. As illustrated in FIGS. 2and 5, the activated gas supply unit 90 includes a plasma generationunit 91, an etching gas supply pipe 92, a shower head unit 93, and apipe 94. Note that the shower head unit 93 is an example of a dischargeunit.

The plasma generation unit 91 activates an etching gas supplied from theetching gas supply pipe 92 using a plasma source. The plasma source isnot particularly limited as long as it is capable of activating thefluorine-containing gas to generate F (fluorine) radicals. For example,an inductively coupled plasma (ICP), a capacitively coupled plasma(CCP), or a surface wave plasma (SWP) may be used as the plasma source.

The etching gas supply pipe 92 has one end that is connected to theplasma generation unit 91 and is configured to supply the etching gas tothe plasma generation unit 91. The other end of the etching gas supplypipe 92 may be connected to an etching gas supply source that stores theetching gas via an on-off valve and a flow regulator, for example. Notethat a gas that is capable of etching the film formed on the wafer W maybe used as the etching gas. Specifically, for example,fluorine-containing gases including hydrofluorocarbons such as CHF₃(trifluoromethane), fluorocarbons such as CF₄ (carbon tetrafluoride) foretching a silicon oxide film may be used. Further, gases such as Ar gas,O₂ gas, and/or H₂ (hydrogen) gas may be added to thesefluorine-containing gases at appropriate amounts, for example.

The shower head unit 93 is connected to the plasma generation unit 91via the pipe 94. The shower head unit 93 supplies the etching gas thathas been activated by the plasma generation unit 91 into the vacuumchamber 1. The shower head unit 93 is fan-shaped in planar view and ispressed downward along the circumferential direction by a press member95 that is formed along the outer edge of the fan shape. The pressmember 95 is fixed to the ceiling plate 11 by a bolt or the like (notshown), and in this way, the internal atmosphere of the vacuum chamber 1may be maintained airtight. The distance between a bottom face of theshower head unit 93 when it is secured to the ceiling plate 11 and asurface of the rotary table 2 may be arranged to be about 0.5 mm to 5mm, for example. A lower region of the shower head unit 93 correspondsto the third process region P3 for etching a silicon oxide film, forexample. In this way, F radicals contained in the activated etching gasthat is supplied into the vacuum chamber 1 via the shower head unit 93may efficiently react with the film formed on the wafer W.

A plurality of gas discharge holes 93 a are arranged at the shower headunit 93. In view of the difference in angular velocity of the rotarytable 2, a smaller number of the gas discharge holes 93 a are arrangedat a rotational center side of the shower head unit 93, and a largernumber of the gas discharge holes 93 a are arranged at an outerperiphery side of the shower head unit 93. The total number of the gasdischarge holes 93 a may be several tens to several hundreds, forexample. Also, the diameter of the plurality of gas discharge holes 93 amay be about 0.5 mm to 3 mm, for example. The activatedfluorine-containing gas supplied to the shower head unit 93 may besupplied to the space between the rotary table 2 and the shower headunit 93 via the gas discharge holes 93 a.

The pipe 94 connects the plasma generation unit 91 and the shower headunit 93.

Also, as illustrated in FIGS. 6 and 7, three purge gas supply units 96(96 a, 96 b, 96 c) are arranged in front of the gas discharge holes 93 awith respect to the circumferential direction of the vacuum chamber 1(upstream side with respect to the rotational direction of the rotarytable 2). The purge gas supply units 96 a-96 c are arranged close to thegas discharge holes 93 a to form integral parts of the shower head unit93.

The purge gas supply units 96 a-96 c are arranged along a radialdirection of the chamber body 12 so as to extend horizontally withrespect to the rotary table 2, and a purge gas is supplied to a spacebetween the rotary table 2 and the shower head unit 93. Each of thepurge gas supply units 96 a-96 c may be connected to an open/close valveand a flow regulator, for example, such that supply flow rate of thepurge gas may be independently controlled at each of the purge gassupply units 96 a-96 c. The flow rate of the purge gas supplied fromeach of the purge gas supply units 96 is controlled based on thedistribution of the etching gas supplied to the surface of the rotarytable 2 by the activated gas supply unit 90.

The purge gas supply unit 96 a is arranged more toward the rotationalcenter side than the purge gas supply unit 96 b along the radialdirection of the chamber body 12. The purge gas supply unit 96 b isarranged more toward the rotational center side than the purge gassupply unit 96 c along the radial direction of the chamber body 12.

By supplying the purge gas from the purge gas supply units 96 a-96 c,the volume fraction of fluorine contained in the etching gas suppliedfrom the gas discharge holes 93 a to the space between the rotary table2 and the shower head unit 93 may be reduced. Note that gases such as Argas or a gas mixture of Ar gas and H₂ gas (hereinafter referred to as“Ar/H₂ gas”) may be used as the purge gas, but Ar/H₂ gas is preferablyused as the purge gas. In this way, F radicals react with the H₂ gas togenerate HF (hydrogen fluoride) such that the amount of F radicals isreduced. That is, the concentration of F radicals may be controlled.

Also, as illustrated in FIGS. 6 and 7, three purge gas supply units 96(96 d, 96 e, 96 f) are arranged behind the gas discharge holes 93 a withrespect to the circumferential direction of the vacuum chamber 1(downstream side with respect to the rotational direction of the rotarytable 2). The purge gas supply units 96 d-96 f are likewise arrangedclose to the gas discharge holes 93 a to form integral parts of theshower head unit 93.

The purge gas supply units 96 d-96 f are arranged along a radialdirection of the chamber body 12 to extend horizontally with respect tothe rotary table 2, and a purge gas is supplied to a space between therotary table 2 and the shower head portion 93. Each of the purge gassupply units 96 d-96 f may be connected to an open/close valve and aflow regulator, for example, such that the supply flow rate of the purgegas may be independently controlled at each of the purge gas supplyunits 96 d-96 f.

The purge gas supply unit 96 d is arranged more toward the rotationalcenter side than the purge gas supply unit 96 e along the radialdirection of the chamber body 12. The purge gas supply unit 96 e isarranged more toward the rotational center side than the purge gassupply unit 96 f in the radial direction of the chamber body 12.

By supplying the purge gas from the purge gas supply units 96 d-96 f,the volume fraction of fluorine contained in the etching gas suppliedfrom the gas discharge holes 93 a to the space between the rotary table2 and the shower head unit 93 may be reduced. Note that the same gas asthat supplied by the purge gas supply units 96 a-96 c such as Ar gas orpreferably Ar/H₂ gas may be used as the purge gas supplied by the purgegas supply units 96 d-96 f, for example.

Note that in FIG. 6, three purge gas supply units 96 are arranged infront of the gas discharge holes 93 a and three purge gas supply units96 are arranged behind the gas discharge holes 93 a with respect to thecircumferential direction of the vacuum chamber 1. However, the presentinvention is not limited to such an arrangement. For example, all of thepurge gas supply units 96 may be arranged only in front of the gasdischarge holes 93 a with respect to the circumferential direction ofthe vacuum chamber 1, or all of the purge gas supply units 96 may bearranged only behind the gas discharge holes 93 a with respect to thecircumferential direction. Also, the number of the purge gas supplyunits 96 arranged at the shower head unit 93 may be any number greaterthan or equal to two.

Also, the substrate processing apparatus of the present embodimentincludes a control unit 100 configured by a computer that performsoverall control operations of the substrate processing apparatus. Thecontrol unit 100 includes a memory that stores a program for causing thesubstrate processing apparatus to implement a substrate processingmethod according to an embodiment of the present invention (describedbelow) under control of the control unit 100. The program includes a setof steps set for performing operations of the substrate processingapparatus (described below) and may be installed in the control unit 100from a storage unit 101 such as a hard disk, a compact disk, an opticaldisk, a memory card, a flexible disk, or some other type ofcomputer-readable storage medium.

(Substrate Processing Method)

In the following, an exemplary substrate processing method using thesubstrate processing apparatus according to the above-describedembodiment is described. Hereinafter, a method of forming a SiO₂ film ina via hole corresponding to an example of a concave pattern that isformed in the wafer W is described as an example. Also, note that in theexample described below, it is assumed that a Si-containing gas is usedas the first reaction gas, an oxidizing gas is used as the secondreaction gas, and a gas mixture of CF₄, Ar gas, O₂ gas, and H₂ gas(hereinafter referred to as “CF₄/Ar/O₂/H₂ gas”) is used as the etchinggas.

First, a gate valve (not shown) is opened, and a wafer W is transferredfrom the exterior by the transfer arm 10 via the transfer port 15 to beplaced within one of the concave portions 24 of the rotary table 2 asillustrated in FIG. 2. The transfer of the wafer W may be accomplishedby lifting the lift pins (not shown) from the bottom side of the vacuumchamber 1 via the through holes that are formed at the bottom face ofthe concave portion 24 when the concave portion 24 comes to a halt at aposition facing the transfer port 15. Such a transfer of the wafer W maybe performed with respect to each of the five concave portions 24 of therotary table 2 by intermittently rotating the rotary table 2 to place awafer W in each of the concave portions 24, for example.

Then, the gate valve is closed, and air is drawn out of the interior ofthe vacuum chamber 1 by the vacuum pump 64. Then, N₂ gas as a separationgas is discharged at a predetermined flow rate from the separation gasnozzles 41 and 42, and N₂ gas is discharged at a predetermined flow ratefrom the separation gas supply pipe 51 and the purge gas supply pipes 72and 73. In turn, the pressure regulating unit 65 adjusts the pressurewithin the vacuum chamber 1 to a preset processing pressure. Then, theheater unit 7 heats the wafers W up to 450° C., for example, while therotary table 2 is rotated clockwise at a rotational speed of 60 rpm, forexample.

Then, a film forming process is performed. In the film forming process,a Si-containing gas is supplied from the reaction gas nozzle 31, and anoxidizing gas is supplied from the reaction gas nozzle 32. Note that inthis process, no gas is supplied from the activated gas supply unit 90.

When one of the wafers W passes the first process region P1, theSi-containing gas as a source gas that is supplied from the reaction gasnozzle 31 is adsorbed to the surface of the wafer W. Then, as the rotarytable 2 is rotated, the wafer W having the Si-containing gas adsorbed toits surface passes the separation region D including the separation gasnozzle 42 where the wafer W is purged. Thereafter, the wafer W entersthe second process region P2. In the second process region P2, theoxidizing gas is supplied from the reaction gas nozzle 32, and Sicomponents contained in the Si-containing gas is oxidized by theoxidizing gas. As a result, SiO₂ corresponding to a reaction product ofthe oxidization is deposited on the surface of the wafer W.

The wafer W that has passed the second process region P2 passes theseparation region D including the separation gas nozzle 41 where thewafer W is purged. Then, the wafer W enters the first process region P1once again. Then, the Si-containing gas that is supplied from thereaction gas nozzle 31 is adsorbed to the surface of the wafer W.

As described above, in the film forming process, the rotary table 2 isconsecutively rotated a plurality of times while supplying the firstreaction gas and the second reaction gas into the vacuum chamber 1 butwithout supplying a fluorine-containing gas into the vacuum chamber 1.In this way, SiO₂ corresponding to the reaction product may be depositedon the surface of the wafer W and a SiO₂ film (silicon oxide film) maybe formed on the wafer W surface.

Also, if necessary or desired, after the SiO₂ film has been formed to apredetermined thickness, the supply of the Si-containing gas from thereaction gas nozzle 31 may be stopped but the oxidizing gas maycontinuously be supplied from the reaction gas nozzle 32 while rotationof the rotary table 2 is continued. In this way, a modification processmay be performed on the SiO₂ film.

By executing the film forming process as described above, the SiO₂ filmmay be formed in a via hole corresponding to one example of a concavepattern. The SiO₂ film that is first formed in the via hole may have across-sectional shape substantially corresponding to the concave shapeof the via hole.

Then, an etching process is performed. In the etching process, the SiO₂film is etched to have a V-shaped cross-sectional shape. In thefollowing, specific process steps of the etching process are described.

As shown in FIG. 2, the supply of the Si-containing gas and theoxidizing gas from the reaction gas nozzles 31 and 32 are stopped, andN₂ gas as a purge gas is supplied. The temperature of the rotary table 2is set to a temperature of about 600° C., for example, that is suitablefor etching. The rotation speed of the rotary table 2 may be set to 60rpm, for example. In such a state, the CF₄/Ar/O₂/H₂ gas is supplied fromthe shower head unit 93 of the activated gas supply unit 90, Ar gas issupplied from the hydrogen-containing gas supply unit 96 at a presetflow rate, for example, and the etching process is started.

Note that at this time, the rotary table 2 is rotated at a relativelylow speed such that the SiO₂ film may be etched to have a V-shapedcross-sectional shape. By etching the S102 film in the via hole into aV-shape, a hole having a wide opening at its top portion may be formedin the SiO₂ film, and in this way, when embedding a SiO₂ film in thehole in a subsequent film forming process, the SiO₂ may reach the bottomof the hole such that bottom-up characteristics may be improved and voidgeneration may be prevented in the film forming process.

Note that when etching the SiO2 film in the etching process, the etchingamount may vary depending on the etching location, namely, from therotational center side to the outer periphery side of the wafer Wsurface. When such a variation in the etching amount is created in thewafer W surface, it is difficult to secure etching uniformity in thewafer W surface.

In view of the above, the substrate processing apparatus according tothe present embodiment has a plurality of purge gas supply units 96arranged on at least one side of the gas discharge holes 93 a withrespect to the circumferential direction of the vacuum chamber 1. Byarranging the purge gas supply units 96 in this manner, Ar gas may besupplied to the space between the rotary table 2 and the shower headunit 93 at a preset flow rate, for example. Also, the flow rate of theAr gas supplied from each of the plurality of purge gas supply units 96may be independently controlled such that the etching amountdistribution within the wafer W surface may be adjusted.

Specifically, when the etching amount at the rotational center side ofthe wafer W surface is large, the flow rate of the Ar gas supplied fromthe purge gas supply unit 96 a may be adjusted to be greater than theflow rate of the Ar gas supplied from the purge gas supply units 96 band 96 c. Note that in the above case, the flow rate of the Ar gassupplied from the purge gas supply unit 96 d may be adjusted to begreater than the flow rate of the Ar gas supplied from the purge gassupply units 96 e and 96 f instead. Moreover, both the Ar gas flow ratesof the purge gas supply units 96 a and 96 d may be adjusted to begreater than the Ar gas flow rates of the other purge gas supply units96.

Also, when the etching amount at the outer periphery side of the wafer Wsurface is large, the flow rate of the Ar gas supplied from the purgegas supply unit 96 c may be adjusted to be greater than the flow rate ofthe Ar gas supplied from the purge gas supply units 96 a and 96 b. Notethat in the above case, the flow rate of the Ar gas supplied from thepurge gas supply unit 96 f may be adjusted to be greater than the flowrate of the Ar gas supplied from the purge gas supply units 96 d and 96e instead. Further, both the Ar gas flow rates of the purge gas supplyunits 96 c and 96 f may be adjusted to be greater than the other purgegas supply units 96.

Note that the flow rate of the Ar gas supplied from each of the purgegas supply units 96 may be controlled by the control unit 100 to flow atpreset flow rate, or the flow rate may be controlled by an operator ofthe substrate processing apparatus, for example.

As described above, in the etching process, the rotary table 2 isrotated consecutively a plurality of times while supplying the etchinggas and the purge gas into the vacuum chamber 1 but without supplyingthe first reaction gas and the second reaction gas into the vacuumchamber 1. In this way, the SiO₂ film may be etched.

Then, the above-mentioned film forming process is performed again. Inthis film forming process, another SiO₂ film is formed on the SiO₂ filmthat has been etched into a V-shape in the above etching process toincrease the film thickness. Because a film is formed on the SiO₂ filmthat has been etched into a V-shape, the opening of the hole in the SiO₂film may be prevented from closing during film formation such that thefilm may be formed from the bottom portion of the SiO₂ film.

Then, the above-mentioned etching process is performed again. In theetching process, the SiO₂ film is etched into a V-shape.

The above-described film forming process and etching process may bealternately performed as many times as necessary to embed the via holewhile preventing the generation of a void in the SiO₂ film. The numberof times these processes are repeated may be adjusted to a suitablenumber according to the shape of the concave pattern (e.g. via hole)such as the aspect ratio of the concave pattern. For example, the numberof repetitions may be increased as the aspect ratio is increased. Also,the number of repetitions is expected to be greater when embedding a viahole as compared to embedding a trench, for example.

Note that in the present embodiment, the film forming process and theetching process are repeatedly performed to embed a film in a concavepattern that is formed in the surface of the wafer W. However, thepresent invention is not limited thereto.

For example, a wafer W already having a film formed on its surface maybe transferred and loaded in the substrate processing apparatus, andonly the etching process may be performed on the wafer W.

Also, in some examples, the first reaction gas, the second reaction gas,the etching gas, and the purge gas may be simultaneously supplied intothe vacuum chamber 1 while consecutively rotating the rotary table 2 aplurality of times, and the film forming process and the etching processmay each be performed once during one rotation cycle of the rotary table2. Further, in some examples, a cycle of performing each of the filmforming process and the etching process once may be repeated a pluralityof times.

EXAMPLES

In the following, results of simulations and experiments conducted usingthe substrate processing apparatus according to the above-describedembodiment are described.

FIGS. 8A-8D are diagrams showing simulation results of the fluorinevolume fraction within the vacuum chamber 1 when CF₄ gas, Ar gas, O₂gas, and H₂ gas (hereinafter referred to as “CF₄/Ar/O₂/H₂ gas”) aresupplied from the activated gas supply unit 90, and Ar gas is suppliedfrom the purge gas supply units 96 (96 a, 96 b, 96 c) that are arrangedin front of the activated gas supply unit 90 with respect to thecircumferential direction of the vacuum chamber 1.

The following simulation conditions were used in the present experiment.That is, the pressure of the vacuum chamber 1 was set to 2 Torr, and thetemperature of the rotary table 2 was set to 600° C., and the rotationalspeed of the rotary table 2 was set to 60 rpm. Also, the Ar gas flowrate of the separation gas supply pipe 51 was set to 0.5 slm, and the Argas flow rate of the purge gas supply pipe 73 was set to 1 slm. Also, atthe etching gas supply pipe 92, the CF₄ gas flow rate was set to 10sccm, the Ar gas flow rate was set to 4 slm, the O₂ gas flow rate wasset to 30 sccm, and the H₂ gas flow rate was set to 20 sccm.

Under the above conditions, the flow rate of the Ar gas supplied fromthe purge gas supply units 96 a, 96 b, and 96 c were varyingly set to100 sccm or 300 sccm, and the fluorine volume fraction within the vacuumchamber 1 was simulated.

FIG. 8A is a diagram showing the simulation result in the case where theflow rates of the Ar gas supplied from the purge gas supply units 96 a,96 b, and 96 c were all set to 100 sccm. FIG. 8B is a diagram showingthe simulation result in the case where the flow rate of the Ar gassupplied from the purge gas supply unit 96 a was set to 300 sccm, andthe flow rates of the Ar gas supplied from the purge gas supply units 96b and 96 c were set to 100 sccm. FIG. 8C is a diagram showing thesimulation result in the case where the flow rate of the Ar gas suppliedfrom the purge gas supply unit 96 b was set to 300 sccm, and the flowrates of the Ar gas supplied from the purge gas supply units 96 a and 96c were set to 100 sccm. FIG. 8D is a diagram showing the simulationresult in the case where the flow rate of the Ar gas supplied from thepurge gas supply unit 96 c was set to 300 sccm, and the flow rates ofthe Ar gas supplied from the purge gas supply units 96 a and 96 b wereset to 100 sccm.

In FIGS. 8A-8D, region Z1 represents a region with the highest fluorinevolume fraction. Further, the fluorine volume fraction being representeddecreases from region Z2 to region Z3, from region Z3 to region Z4, fromregion Z4 to region Z5, from region Z5 to region Z6, from region Z6 toregion Z7, from region Z7 to region Z8, from region Z8 to region Z9, andfrom region Z9 to region Z10.

Referring to FIGS. 8A-8D, it can be appreciated that in regions locatedin front of the purge gas supply units 96 with respect to thecircumferential direction, the fluorine volume fraction is lower in thecase where the Ar gas flow rate is set to 300 sccm as compared to thecase where the Ar gas flow rate is set to 100 sccm. More specifically,in FIGS. 8B-8D as compared to FIG. 8A, the area of region Z4 is smallerand the areas of regions Z5 and Z6 are larger in the region located infront of the purge gas supply unit 96 that has been set up to supply theAr gas at the flow rate of 300 sccm. That is, by increasing the Ar gasflow rate of one or more of the purge gas supply units 96, the fluorinevolume fraction may be decreased in the region located in front of thepurge gas supply unit 96 that has been set up to supply the Ar gas atthe increased flow rate. As a result, the silicon oxide film etchingamount in the corresponding region may be reduced.

FIGS. 9A-9C are diagrams similar to FIGS. 8A-8D showing simulationresults of the fluorine volume fraction within the vacuum chamber 1 whenthe CF₄/Ar/O₂/H₂ gas is supplied from the activated gas supply unit 90,and Ar gas is supplied from the purge gas supply units 96 (96 a, 96 b,96 c) that are arranged in front of the activated gas supply unit 90with respect to the circumferential direction of the vacuum chamber 1.Note that in FIGS. 9A-9C, simulation conditions similar to those ofFIGS. 8A-8D were used, but the flow rates of Ar gas supplied from thepurge gas supply units 96 a-96 c were varyingly set to 100 sccm or 1000sccm, and the fluorine volume fraction within the vacuum chamber 1 wassimulated under these conditions.

FIG. 9A is a diagram showing the simulation result in the case where theflow rate of the Ar gas supplied from the purge gas supply unit 96 a wasset to 1000 sccm, and the flow rates of the Ar gas supplied from thepurge gas supply units 96 b and 96 c were set to 100 sccm. FIG. 9B is adiagram showing the simulation result in the case where the flow rate ofthe Ar gas supplied from the purge gas supply unit 96 b was set to 1000sccm, and the flow rates of the Ar gas supplied from the purge gassupply units 96 a and 96 c were set to 100 sccm. FIG. 9C is a diagramshowing the simulation result in the case where the flow rate of the Argas supplied from the purge gas supply unit 96 c was set to 1000 sccm,and the flow rates of the Ar gas supplied from the purge gas supplyunits 96 a and 96 b were set to 100 sccm.

In FIGS. 9A-9C, region Z1 represents a region where the fluorine volumefraction is the highest. Further, the fluorine volume fraction beingrepresented decreases from region Z2 to region Z3, from region Z3 toregion Z4, from region Z4 to region Z5, from region Z5 to region Z6,from region Z6 to region Z7, from region Z7 to region Z8, from region Z8to region Z9, and from region Z9 to region Z10.

Referring to FIG. 8A and FIGS. 9A-9C, it can be appreciated that in theregions located in front of the purge gas supply units 96 with respectto the circumferential direction, the fluorine volume fraction is lowerin the case where the Ar gas flow rate is set to 1000 sccm as comparedto the case where the Ar gas flow rate is set to 100 sccm. Morespecifically, in FIGS. 9A-9C as compared to FIG. 8A, the area of regionZ4 is smaller and the areas of regions Z5 and Z6 are larger in theregion located in front of the purge gas supply unit 96 that has beenset up to supply the Ar gas at the flow rate of 1000 sccm. That is, byincreasing the Ar gas flow rate of one or more of the purge gas supplyunits 96, the fluorine volume fraction may be decreased in the regionlocated in front of the purge gas supply unit 96 that has been set up tosupply the Ar gas at the increased flow rate. As a result, the siliconoxide film etching amount in the corresponding region may be reduced.Further, by increasing the Ar gas flow rate from 300 sccm to 1000 sccm,the fluorine volume fraction may be further decreased as compared to thecase where the Ar gas flow rate is set to 300 sccm.

FIGS. 10A-10D are diagrams showing simulation results of the fluorinevolume fraction within the vacuum chamber 1 when the CF₄/Ar/O₂/H₂ gas issupplied from the activated gas supply unit 90, and Ar gas is suppliedfrom the purge gas supply units 96 (96 d, 96 e, 96 f) that are arrangedbehind the activated gas supply unit 90 with respect to thecircumferential direction of the vacuum chamber 1. Note that in FIGS.10A-10D, the flow rates of Ar gas supplied from the purge gas supplyunits 96 d-96 f were varyingly set to 100 sccm or 300 sccm undersimulation conditions similar to those of FIGS. 8A-8D, and the fluorinevolume fraction within the vacuum chamber 1 was simulated under theseconditions.

FIG. 10A is a diagram showing the simulation result in the case wherethe Ar gas flow rates of the purge gas supply units 96 d-96 f were allset to 100 scm. FIG. 10B is a diagram showing the simulation result inthe case where the flow rate of the Ar gas supplied from the purge gassupply unit 96 d was set to 300 sccm, and the flow rates of the Ar gassupplied from the purge gas supply units 96 e and 96 f were set to 100sccm. FIG. 10C is a diagram showing the simulation result in the casewhere the flow rate of the Ar gas supplied from the purge gas supplyunit 96 e was set to 300 sccm, and the flow rates of the Ar gas suppliedfrom the purge gas supply units 96 d and 96 f were set to 100 sccm. FIG.10D is a diagram showing the simulation result in the case where theflow rate of the Ar gas supplied from the purge gas supply unit 96 f wasset to 300 sccm, and the flow rates of the Ar gas supplied from thepurge gas supply units 96 d and 96 e were set to 100 sccm.

In FIGS. 10A-10D, region Z1 represents a region where the fluorinevolume fraction is the highest. Further, the fluorine volume fractionbeing represented decreases from region Z2 to region Z3, from region Z3to region Z4, from region Z4 to region Z5, from region Z5 to region Z6,from region Z6 to region Z7, from region Z7 to region Z8, from region Z8to region Z9, and from region Z9 to region Z10.

Referring to FIGS. 10A-10D, it can be appreciated that in regionslocated behind the purge gas supply units 96 with respect to thecircumferential direction, the fluorine volume fraction is lower in thecase where the Ar gas flow rate is set to 300 sccm as compared to thecase where the Ar gas flow rate is set to 100 sccm. More specifically,in FIGS. 10B-10D as compared to FIG. 10A, the area of region Z4 issmaller and the areas of regions Z5 and Z6 are larger in the regionlocated behind the purge gas supply unit 96 that has been set up tosupply the Ar gas at the flow rate of 300 sccm. That is, by increasingthe Ar gas flow rate of one or more of the purge gas supply units 96,the fluorine volume fraction may be decreased in the region locatedbehind the purge gas supply unit 96 that has been set up to supply theAr gas at the increased flow rate. As a result, the silicon oxide filmetching amount in the corresponding region may be reduced. Further, byarranging the purge gas supply units 96 behind the activated gas supplyunit 90 with respect to the circumferential direction, Ar gas that issupplied from the purge gas supply unit 96 that is arranged at a centerwith respect to the radial direction of the vacuum chamber 1 may beprevented from flowing toward the outer periphery side with respect tothe radial direction of the vacuum chamber 1. In this way,controllability of the fluorine volume fraction may be improved.

As described above, according to an aspect of the substrate processingapparatus and the substrate processing method of the present embodiment,the etching amount distribution in a substrate surface may becontrolled.

Although a substrate processing apparatus and a substrate processingmethod according to the present invention have been described above withrespect to certain illustrative embodiments, the present invention isnot limited to the above embodiments, and various variations andmodifications may be made within the scope of the present invention.

For example, in the above descriptions, an embodiment in which theplasma generation unit 91 of the activated gas supply unit 90 isarranged above the shower head unit 93 via the pipe 94 is illustrated.However, the position of the plasma generation unit 91 is notparticularly limited as long as it is arranged at a suitable positionsuch that a fluorine-containing gas may be activated and supplied to afilm that is formed on a wafer W. For example, the plasma generationunit 91 may be arranged inside the shower head unit 93 or below theshower head 93.

The present application is based on and claims the benefit of priorityto Japanese Patent Application No. 2015-041500 filed on Mar. 3, 2015,the entire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A substrate processing apparatus comprising: avacuum chamber; a rotary table that is rotatably arranged in the vacuumchamber to hold a substrate; a first reaction gas supply unit thatsupplies a first reaction gas to a surface of the rotary table; a secondreaction gas supply unit that is arranged apart from the first reactiongas supply unit in a circumferential direction of the rotary table andsupplies a second reaction gas, which reacts with the first reactiongas, to the surface of the rotary table; an activated gas supply unitthat is arranged apart from the first reaction gas supply unit and thesecond reaction gas supply unit in the circumferential direction of therotary table, the activated gas supply unit including a discharge unithaving a discharge hole through which an etching gas that has beenactivated is supplied to the surface of the rotary table; and aplurality of purge gas supply units that are provided near the dischargehole with respect to the circumferential direction of the rotary tableand supply a purge gas to the surface of the rotary table; wherein aflow rate of the purge gas supplied from each of the plurality of purgegas supply units can be independently controlled.
 2. The substrateprocessing apparatus according to claim 1, wherein the plurality ofpurge gas supply units are arranged close to each other along a radialdirection of the rotary table.
 3. The substrate processing apparatusaccording to claim 1, wherein the plurality of purge gas supply unitsare arranged at an upstream side of the discharge hole with respect to arotational direction of the rotary table.
 4. The substrate processingapparatus according to claim 3, wherein the plurality of purge gassupply units are integrated with the discharge unit.
 5. The substrateprocessing apparatus according to claim 1, wherein more discharge holesare arranged at a rotational center side of the rotary table than at anouter periphery side of the rotary table.
 6. The substrate processingapparatus according to claim 1, wherein the first reaction gas is asilicon-containing gas; the second reaction gas is an oxidizing gas; theetching gas is a fluorine-containing gas; and the purge gas is ahydrogen-containing gas.
 7. The substrate processing apparatus accordingto claim 1, further comprising: a control unit that controls the flowrate of the purge gas supplied from each of the purge gas supply unitsbased on a distribution of the etching gas supplied to the surface ofthe rotary table by the activated gas supply unit.
 8. The substrateprocessing apparatus according to claim 7, wherein the control unitsupplies the first reaction gas and the second reaction gas from thefirst reaction gas supply unit and the second reaction gas supply unit,respectively, and refrains from supplying the etching gas from theactivated gas supply unit when performing only a film forming process ona surface of the substrate; and the control unit refrains from supplyingthe first reaction gas and the second reaction gas from the firstreaction gas supply unit and the second reaction gas supply unit, andsupplies the etching gas and the purge gas from the activated gas supplyunit and the purge gas supply unit, respectively, when performing onlyan etching process on a film that has been formed on the surface of thesubstrate.
 9. A substrate processing method comprising: an etching stepof mounting a substrate on a surface of a rotatory table arranged in avacuum chamber and supplying an etching gas into the vacuum chamberwhile rotating the rotary table to etch a film formed on a surface ofthe substrate; wherein the etching step includes supplying the etchinggas to the surface of the rotary table and supplying a purge gas from aplurality of purge gas supply units that are provided near a regionwhere the etching gas is supplied; and controlling an etching amount ofetching the film by independently varying a flow rate of the purge gasthat is supplied from each of the plurality of purge gas supply units.10. The substrate processing method according to claim 9, wherein a flowrate of the purge gas supplied from each of the plurality of purge gassupply units is varied based on a distribution of the etching gassupplied to the surface of the rotary table.
 11. The substrateprocessing method according to claim 10, wherein the flow rate of thepurge gas is decreased to increase the etching amount, and the flow rateof the purge gas increased to decrease the etching amount.
 12. Thesubstrate processing method according to claim 9, further comprising afilm forming step of supplying a first reaction gas and a secondreaction gas, reacts with the first reaction gas, into the vacuumchamber while rotating the rotary table to form the film on the surfaceof the substrate.
 13. The substrate processing method according to claim12, wherein the film forming step includes a step of supplying the firstreaction gas and the second reaction gas into the vacuum chamber withoutsupplying the etching gas into the vacuum chamber while consecutivelyrotating the rotary table a plurality of times; and the etching stepincludes a step of supplying the etching gas and the purge gas into thevacuum chamber without supplying the first reaction gas and the secondreaction gas into the vacuum chamber while consecutively rotating therotary table a plurality of times.
 14. The substrate processing methodaccording to claim 12, wherein the first reaction gas, the secondreaction gas, the etching gas, and the purge gas are simultaneouslysupplied into the vacuum chamber while consecutively rotating the rotarytable a plurality of times; and the film forming step and the etchingstep are each performed once during one rotation cycle of the rotarytable, and the rotation cycle is repeated a plurality of times.